


sending signals (to be double crossed)

by sixtywattgloom



Category: The Locked Tomb Trilogy | Gideon the Ninth Series - Tamsyn Muir
Genre: Gen, but she cares about him so a little it just seems unfair to him, canon-typical badtwins content cw, help them their relationship is a mess, i probably could have included a corona & babs tag too, just 2 kids who understand everything and nothing about each other, or don't because i love suffering, suggestive of suicide via lyctorhood, very minor and brief self-harm in the form of biting (as one does)
Language: English
Status: Completed
Published: 2021-02-20
Updated: 2021-02-20
Packaged: 2021-03-16 04:27:05
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,766
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29570295
Author URL: https://archiveofourown.org/users/sixtywattgloom/pseuds/sixtywattgloom
Summary: She is Ida’s Crown Princess; she has made a home in the heart of every person she has ever met, and in the heart of every person she has left behind; the force of her smile is – as one (“profoundly trite,” as told by her twin) poet noted – rivaled only by Dominicus from the eyes of the Sixth, had they the temerity to carve windows in their libraries. And she can do nothing.or, the one about coronabeth's complicated relationship to (not) being a cavalier.
Relationships: Coronabeth Tridentarius & Ianthe Tridentarius
Comments: 8
Kudos: 36





	sending signals (to be double crossed)

**Author's Note:**

> just here to have fun with my first official foray into tm's sandbox by way of the worst girls, so hopefully there's something in here you enjoy, too?

“Tell me everything,” Coronabeth used to say, when it still needed to be said; now it requires no more than a smile, bright and just the right measure of inviting—the hot, invigorating rush of the duel cooling in their wake—and Babs knows exactly what she needs.  
  
Corona would defy anyone to claim Babs can’t be trained; lead the boy to water, and he will drain it dry, _especially_ if you offer a please. (Corona doesn’t always feel like saying please, but Corona’s never needed to.)

Nevertheless, today’s duel had been the kind that makes Coronabeth hate their cavalier a bit—not that it’s Babs’ fault, the poor boy. It has nothing at all to do with him, really; very little ever has to do with Babs. And if it weren’t Babs, it would be someone else, and Corona would still be living her life watching from the sidelines, the heady rush of adrenaline infinitely unfulfilled.

His opponent had been well and truly remarkable, a fact enough on its own to kindle Corona’s (small bit of) loathing—especially in combination with Babs’ every lovely parry, and the lightness of his footwork that had only barely been enough today. She hated him gently for the moment he’d read wrong: that fraction of a second he fell behind when she moved right, and he expected left.

It was thrilling, of course: Corona devours every opportunity to watch—better still, to arbitrate—like it’s the best dessert, sweet and rich, the kind that she consumes ceaselessly and regrets only when she wakes in the middle of the night to nausea twisting her stomach and Ianthe delivering some variation of _I told you so_ while she holds back her hair.

But her favorite part of all is the part that comes afterward: the _tell me everything_ that fits in the shape of her smile, encouragement enough for Babs to guide her through each step of the duel the moment they’re alone. He needs very little nudging, beyond that; her request combines, after all, his three favorite subjects—duels, winning, and himself—recounted to serve the pleasure of a girl he regards with the kind of earnest interest that might on occasion be mistaken for devotion.

“How did it _feel_?” she nearly always asks, and he indulges her by relating the thrill and certainty of the final touch, the way his heart leapt into his throat.

Today, Ianthe’s mood is sour. She lounges in the chair by the window, one leg draped over one of the armrests; on the other rests her arm, propping up her head. “She almost had you,” Ianthe says. ( _Alone_ is only occasionally shaped like Corona; more often than not it fits Corona-and-Ianthe, as it always has.) “It might be time we reconsider our choice in cavalier.”

“Don’t be absurd,” he says. Babs’ mood is irrelevant; he will always make time for bouts with Ianthe. “She’d stand no chance against me. I could challenge her again where we stand, and the result would be the same.”

“She’s teasing you, Babs,” says Corona.

“Who says?” objects Ianthe. “ _I’m_ evaluating our options. One really ought to be smart about one’s investments.”  
  
  
  
  
  
Corona lunges at him, sweat pouring from her brow; the rapier has become a comfortable, easy weight in her hand, and she’s fast enough now that he miscalculates. It’s only by a hair, but it’s enough: the blade makes contact with his collarbone.

It’s her first victory against him; she watches his mouth twist in surprise, but when she turns, it’s to find her sister’s face, observing from the sidelines. Ianthe’s slow to rise, and her applause slower still as she approaches; Corona, breathless with exertion and victory, wraps her arms around Naberius, ruffling his hair in earnest. “Oh, beginner’s luck must have finally caught up to me after all,” she says—in certain areas, Babs has always needed a little coaxing. “Though I suppose that’s the natural luck that results from having acquired such a gifted teacher.”

“Princess, you did remarkably,” he says, after only another moment, having apparently navigated the tangle of complex emotions stemming from the intersection of _losing a duel_ and _Coronabeth_ more quickly than Corona expected.

“Congratulations,” says Ianthe idly, now by her side. When she touches a hand briefly to Corona’s cheek, just long enough for a condescending pat or two, it strikes Corona as colder than she expected—but she drops it, and the feeling is gone. “You’ve bested _Babs_. What higher heights remain to be reached?”

“You were the one who said I’d never have the stamina for it,” Corona points out, still a little breathless.

“Well, who among us could forget your three-day foray into fashion design? Or your thirty-second-long career as a master painter?” says Ianthe. “And your lifelong commitment to reading—a remarkable two weeks. Your signature triumph.”

“I read nightly,” argued Corona.

“ _I_ read nightly,” said Ianthe. “You listen nightly. Sometimes you even give the gift of consciousness at the end of the first chapter. It more than triples my reading time, you know.”

“No one would guess what a trial it was for you,” Babs says suddenly from beside them, reminding Corona that he’s still in the room. His tendency to consider Corona and Ianthe arguing in front of him an implicit invitation that he become party to a side (Corona’s) is as tiresome as it’s ever been. “The way you go on, you’d think you were delivering it from a stage.”

“He’s right, Ianthe,” Corona says breezily, still too victorious to consider bothering a wit about Babs’ latest hissy fit. “None of those historical romances are the same without your voices. I can’t imagine Aster’s necromancer sounding like anyone but Abigail Pent.”

Long moments stretch between them, as Ianthe watches her with a look not unlike the one she gets whenever she’s working her way through some especially trying calculation. “Just try to recall,” Ianthe says finally, leaning forward to curl a hand around Corona’s upper arm, where new muscle flexes beneath it; her grasp is tight enough that it might have hurt, were she capable of so much as lifting one of her books higher than her chin, “that you are a _necromantic_ Princess of Ida.”  
  
  
  
  
  
Coronabeth Tridentarius can do nothing.

It’s like she’s released all the breath from her lungs, all at once, in a rush both exhilarating and terrifying, and only just begun to reckon with what remains behind.

She is Ida’s Crown Princess; she has made a home in the heart of every person she has ever met, and in the heart of every person she has left behind; the force of her smile is – as one (“profoundly trite,” as told by her twin) poet noted – rivaled only by Dominicus from the eyes of the Sixth, had they the temerity to carve windows in their libraries. And she can do nothing.

“You should be happier, baby,” Ianthe offers, back in their room, a kind of patronizing coo. “Haven’t you got your key, now? Isn’t it all you ever wanted?”

“I should be your cavalier. By rights, I should be your cavalier,” Corona says, instead of answering – as if it were ever about the key itself, and not always about her sister: skulking in the shadows and gathering secrets to stow away from prying eyes, like Corona’s eyes and Babs’ eyes are interchangeable. Like Corona could have been of the Sixth or the Second or even the Ninth for all that her sister is willing to offer. But she sets her jaw, like the cavalier primary of any good historical would when making her final stand. It’s a role she has waited a lifetime to claim; she will not skimp on the audition. “What is Babs to you but a boy with a sword and the audacity to treat you as less than you are?”

“Your _rights_ are to a throne,” Ianthe says, with a voice that gestures toward nonchalance. “And Babs has his role to play.” But she is troubled; Corona would recognize the slope of her brow in the blackness of space. She takes it as an opening. (There is little that Corona cannot shape into a doorway, when she has always carried the master key.)

“What role can he play that I cannot?” Corona demands. “ _I_ will swear the vow to you now. I will get on my knees and pledge myself to your service.” She does not wait for Ianthe’s answer; she drops to her knees with the grace of the Crown Princess of Ida but the force of a cavalier, and stares into the matching eyes of her twin, her own ablaze. “You do not need him. You need only me, as I have only ever needed you. Everything else is artifice.”

“Stand up,” Ianthe says. “You look more fool than cavalier. The perils of Babs as the blueprint, I suppose. God, imagine if Mummy could see you now—you’d be the one to bring shame to the family at last.” Ianthe attempts to walk the line between amused and cutting, but genuine concern is so rare an emotion on her it is impossible for Corona to miss; she watches it curl up at the corner of Ianthe’s mouth and she watches it direct the posture of her shoulders.

Still, Corona doesn’t move; instead, in what she considers a striking act of defiance, she reaches for her sister’s hand and grabs it in both of hers. “I will challenge him now, if it takes that. If it is a matter of ability, I could lay him low.”

“Coronabeth,” says Ianthe, “you look stupid on your knees.” As she pulls her hand from Corona’s grip—hard, for a moment harder than Corona would have believed possible of her sister—and turns toward the door, she says, “You don’t have the imagination to begin to comprehend what it is you’re asking.” And then she’s gone.

Corona does not move. She thinks of Aster Trey’s vigil for her necromancer; she thinks of her silent, poetic tears, of her head pressed to the ground, of her hand wrapped around the hilt of her sword—the picture of devotion, her eyes clear and sad and beautiful, her blouse magnificent and revealing. Corona’s knees ache; Corona’s throat aches. Ianthe has always taken great pleasure in being the only person who could ever tell her no.

It’s Naberius who finds her, hours (well, perhaps minutes—but a great many of them) later; she lets him hold her with little protest, and he lets her bite uselessly at the skin of his forearm with even less. The taste of him turns strangely to ash in her mouth, as she considers lunging for the hilt of his rapier, suddenly desperate to pit her reflexes against his in a way that matters.

Instead, she buries her face into his neck and thinks that perhaps there has never been space at all for her in Ianthe’s _alone_.  
  
  
  
  
  
Corona watches as Ianthe begins a ritual Corona could never hope to fathom, and realizes that her sister had been right about one thing: she had not comprehended the nature of her own request.

Had she understood, she would have made the demand every day, every hour, every second—she would have begged to be cast in the part she most deserved from the very moment they understood what Ianthe had, and what Corona did not. She would have spent her life on hands and knees; she would have practiced with the rapier until she could no longer feel anything but the burn of it; she would have rescinded all claim to the throne; Emperor Undying, she would have removed every wisp of hair from her head, were it deemed more suitable for the position. She would have given herself over to be siphoned, in the profoundly grotesque manner of the Eighth (albeit with better skin) if the guarantee was that, at the end of all things, Coronabeth would be Ianthe would be Coronabeth—if the way that they ended was the way that they began, only forever.

“Ianthe,” she says, “don’t you dare.” She can feel now that she is crying, though only distantly, in the manner someone faced with an alarm inches away from their face might comprehend vaguely the sound of a voice a room away.

“This is what it is to be a Lyctor,” says Ianthe, answering the wrong question entirely. “It’s almost complete. I’ve done it. Coronabeth, I’ve blown the whole thing wide open.”

“Choose me as your cavalier,” insists Corona, lest Ianthe devolve into specifics about equations Corona neither hopes nor cares to understand, only she hears herself choke on it.

“There will no longer _be_ any cavalier,” says Ianthe; her concentration is costing her patience, but even Corona can see she’s near completion, by the state of her. “Are you really so dense you can’t see we’ve reached dear Babs’ final hour? He won’t _exist_. I’ll have eaten him all up. My, what big teeth I have.”

Whatever has been keeping Corona from approaching her sister—more a mist than a shield, though it’s heavy and pink and wreaks absolute havoc with her hair—fades as Ianthe reaches for the hilt of Babs’ rapier, her focus narrowing.

“One flesh, one end,” Corona says; the tears sliding down her cheeks remain an afterthought, though her voice trembles with them. Louder, she says: “One flesh, one end.”

“God, Corona,” Ianthe says, through gritted teeth, “there is nothing you can do to stop me, so you could at least do us both the generous favor of keeping your mouth shut for once in your—”

But the words catch as Corona reaches for Ianthe’s hand—the one wrapped around the blade—and crawls in front of the very unconscious body of Prince Naberius Tern, a shield by incident, a magnet by design. “I can do one thing,” she says, overpowering her sister in the space of a heartbeat. “One flesh,” she says, ferocious in a way that is less Cavalier Primary Protagonist and more fairy tale beast, a threat to kingdoms long dead, “one end.”

From there, it becomes easier than it should: easy to guide Ianthe and Babs’ blade exactly where she wants them, easy to pierce first the fabric, and then the skin. It’s true that Corona can’t unspool theorems, but, she thinks, meeting Ianthe’s eyes, she knows precisely how to find the heart.

Corona leans forward, into the sword and toward Ianthe; she slides her fingers through her sister’s hair, and presses their foreheads together. “One flesh, one end,” she hears Ianthe whisper back, in a voice unlike any she’s ever heard.

Corona’s vision begins to darken around the edges, but her mind is remarkably clear: she has lived a fractured life, and waited more than two decades to make it whole.

Except that the next thing she feels is a hand on her cheek—cold to the touch, and not half as soft as it should be. “Darling,” she hears, as her vision, impossibly, clears. When she reluctantly opens her eyes the rest of the way, she finds she’s faced with a sight so gruesome as to be unmatched: Babs’ eyes in her sister’s face—and the inexplicable feeling of bone gently cupping her chin. “You know this isn’t how it happens.”  
  
  
  
  
  
Coronabeth Tridentarius wakes with a start, violent and furious, and makes a sound too low to be a scream.

She is alone. If she stills for long enough, she can hear the distant sound of heavy breathing through the improbably thin walls, but her bed is empty, and her sheets—built for utility, never to be mistaken for luxury—are damp with sweat. Her hair sticks to her forehead; when she brings a palm to her chest, she finds the stark evidence of a vow unfulfilled in every inch of unblemished skin.

Without coherent thought, she bites into the skin of her wrist, impotent and trembling with a lifetime of fury made smooth for public consumption: never necromancer, never cavalier. It has been many nights since Corona last cried; her anger is jagged, now, and it has crowded out and speared through every other emotion that might have thought to replace it, except the foundation of betrayal from which it grows.

Coronabeth tightens her hand into a fist, hard enough to hurt. And she wonders if there is a stranger with the wrong eyes, millions or billions of lightyears away, who dreams of a palm that stings in the shape of a kiss left by a girl she never loved.

**Author's Note:**

> yes i did have a good time getting to handwave lots of logistical and timeline things that came from this basically all happening in corona's head thank you for asking!!! the handshake meme is me, tm, & "loving an unreliable narrator."


End file.
